The present exemplary embodiment relates generally to compensation of banding from multiple sources in a marking platform. It finds particular application in conjunction with a multicolor marking platform with xerographic marking engines. However, it is to be appreciated that the exemplary embodiments described herein are also amenable to various other types of marking engines and other types of marking platforms.
Banding is a type of image quality defect that occurs on printed pages. It manifests itself as a variation in density with respect to the process direction. Most banding is periodic. Periodic density variations may be characterized by frequency, amplitude, and phase in relation to a fundamental frequency, as well as harmonics. Various sources of banding exist in a marking (or print) engine. The frequencies of these sources are typically known based on the mechanical design of the engine. The frequencies, for example, may be obtained from the manufacturer, third parties, or measured. To compensate for the banding effects, the amplitude and phase also need to be obtained from measurements.
Recent work has identified techniques for identifying banding sources using measurements of test patterns on paper, using a multipage coherent fast Fourier transform (FFT) technique to identify the banding sources. Further, a cubic spline interpolation technique has been used to fit banding profiles to single known sources, such as photoreceptor (PR) 1×. The cubic spline interpolation technique has also been applied to derive an optimal exposure correction for single known sources across the tone reproduction curve (TRC) for banding compensation. However, these techniques require interrupting the print job to print several test images and additional offline processing to determine the correction. Further, these techniques use once around (1×) sensors on the components that may cause banding.